Human chorionic gonadotropin (CG) biosynthesis has been studied at a pretranslational level. Single stranded RNA probes have been developed for both the alpha and beta subunits of CG, and have provided a more sensitive hybridization assay for the detection of CG messenger RNA. Cyclic AMP analogs regulate alpha and beta messenger RNA in eutopic human cancer cell lines, while butyrate regulates alpha messenger RNA in ectopic lines. Macromolecular forms of human placental lactogen have been characterized.